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Schubert, Markus M.; Plzak, V.; Garche, Jürgen; Behm, R. Jürgen

doi:10.1023/a:1012365710979

Cited by 249 publications

(163 citation statements)

References 25 publications

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“…Activity of nanoparticles of gold on non-oxide supports has also been reported [16]. The preferential oxidation of CO (PROX) has been reported to take place on nanoscale gold on oxide supports with high selectivity at temperatures below 120°C even in realistic fuel gas mixtures [17][18][19]. In the search for a new generation of low-temperature water-gas shift (WGS) catalysts to replace the low-stability Cu-ZnO, which is unsuitable for fuel cell applications, Au-based catalysts are being actively studied.…”

Section: Introductionmentioning

confidence: 90%

“…Leaching of gold from calcined goldceria and gold-iron oxide samples took place in an aqueous solution of 2% NaCN under O 2 gas sparging at room temperature and high pH ( ‡12). After washing by deionized water, the leached catalysts were dried for 12 h at 100°C and calcined at 400°C for 2 h. A sample of Fe 2 O 3 was prepared by coprecipitation according to a method described by Schubert et al [17] who used it to prepare Au/a-Fe 2 O 3 . Iron nitrate solution was added dropwise to 500 mL deionized water containing sodium carbonate at pH $8.…”

Section: Sample Preparationmentioning

confidence: 99%

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Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

et al. 2007

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We compare the activity and relevant gold species of nanostructured gold-cerium oxide and gold-iron oxide catalysts for the CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze the water-gas shift reaction. Gold species weakly bound to ceria (doped with lanthana) or iron oxide can be removed by sodium cyanide at pH ‡12. Both parent and leached catalysts were investigated. The activity of the leached gold-iron oxide catalyst in CO oxidation is approximately two orders of magnitude lower than that of the parent material. However, after exposure to H 2 up to 400°C gold diffuses out and is in reduced form on the surface, a process accompanied by a dramatic enhancement of the CO oxidation activity. Similar results were found with the gold-ceria catalysts. On the other hand, pre-reduction of the calcined leached catalyst samples did not promote their water-gas shift activity. UV-Vis, XANES and XPS were used to probe the oxidation state of the catalysts after various treatments.

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Section: Introductionmentioning

confidence: 90%

Section: Sample Preparationmentioning

confidence: 99%

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

et al. 2007

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“…Stable carbonate intermediates have been observed on the surface in several IR studies of real catalysts (191,358,375,377,403,421,422,430,473). Originally thought to be a key part of the mechanism (191,473), the prevailing view today is that CO3 is a spectator species in the reaction (3,4,496) and that it can even act to deactivate the catalyst by blocking reaction sites (382,467,(500)(501)(502)(503). However, the transition could very well be a non-symmetrical carbonate such that preferential cleavage of the O-OCO bond is conceivable as has been proposed by both theorists and experimentalists (226,247,474).…”

Section: 2mentioning

confidence: 99%

Surface chemistry of catalysis by gold

et al. 2004

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IntroductionGold has long been regarded as an "inert" surface and bulk gold surfaces do not chemisorb many molecules easily. However, in the last decade, largely through the efforts of Masatake Haruta, gold particles, particularly those below 5 nm in size, have begun to garner attention for unique catalytic properties (1-8). In recent years, supported gold particles have been shown to be effective as catalysts for low temperature CO oxidation (9), selective oxidation of propene to propene oxide (10), water gas shift (11), NO reduction (12), selective hydrogenation of acetylene (or butadiene) (13)

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“…Supported Au catalysts are known to be prone to the formation of carbonate-like compounds [31,[68][69][70][71][72]. Previous studies have correlated carbonates formation with catalytic activity, pretreatment conditions [23,73], presence of moisture in the gas [10,16], and reaction temperature [74].…”

Section: Loss Of Active Sites and Carbonates Buildupmentioning

confidence: 99%

CO oxidation over Au/TiO2 catalyst: Pretreatment effects, catalyst deactivation, and carbonates production

Lopez

Powell

Panthi

et al. 2013

Journal of Catalysis

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a b s t r a c tA commercially available Au/TiO 2 catalyst was subjected to a variety of thermal treatments in order to understand how variations in catalyst pretreatment procedures might affect CO oxidation catalysis. Catalytic activity was found to be inversely correlated to the temperature of the pretreatment. Infrared spectroscopy of adsorbed CO experiments, followed by a Temkin analysis of the data, indicated that the thermal treatments caused essentially no changes to the electronics of the Au particles; this, and a series of catalysis control experiments, and previous transmission electron microscopy (TEM) studies ruled out particle growth as a contributing factor to the activity loss. Fourier transform infrared (FTIR) spectroscopy showed that pretreating the catalyst results in water desorption from the surface, but the observable water loss was similar for all the treatments and could not be correlated with catalytic activity. A Michaelis-Menten kinetic treatment indicated that the main reason for deactivation is a loss in the number of active sites with little changes in their intrinsic activity. In situ FTIR experiments during CO oxidation showed extensive buildup of carbonate-like surface species when the pretreated catalysts were contacted with the feed gas. A semi-quantitative infrared spectroscopy method was developed for comparing the amount of carbonates present on each catalyst; results from these experiments showed a strong correlation between the steady-state catalytic activity and amount of surface carbonates generated during the initial moments of catalysis. Further, this experimental protocol was used to show that the carbonates reside on the titania support rather than on the Au, as there was no evidence that they poison Au-CO binding sites. The role of the carbonates in the reaction scheme, their potential role in catalyst deactivation, and the role of surface hydroxyls and water are discussed.

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Untitled

Cited by 249 publications

References 25 publications

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Surface chemistry of catalysis by gold

CO oxidation over Au/TiO2 catalyst: Pretreatment effects, catalyst deactivation, and carbonates production

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